diff --git a/tests-extra/tests/dnssec/ksk_rollover/test.py b/tests-extra/tests/dnssec/ksk_rollover/test.py
index 5e19012e93ea1be712ead62648bb693de3fb77f5..984ec4fb8b5448df9dcedcc010d1b661b6e0a7a4 100644
--- a/tests-extra/tests/dnssec/ksk_rollover/test.py
+++ b/tests-extra/tests/dnssec/ksk_rollover/test.py
@@ -119,7 +119,7 @@ def watch_ksk_rollover(t, server, zone, before_keys, after_keys, total_keys, des
     check_zone(server, zone, server, total_keys, 2, 0, 1, msg)
 
     msg = desc + ": new KSK ready"
-    wait_for_cds_change(t, server, 16, 26, msg) # propagation-delay + dnskey_ttl
+    wait_for_cds_change(t, server, 15, 26, msg) # propagation-delay + dnskey_ttl
     check_zone(server, zone, server, total_keys, 2, 1, 1, msg)
 
     submission_cb()